(1) Field of the Invention
This invention relates to a method of editing image signal and, more particularly, to a method of editing image signal for use in an image processing system such as layout scanner system in which a plurality of image data such as color plate signals obtained by applying such process as tone correction or magnification change to color separating image signals obtained by scanning sequentially a plurality of color original pictures are once individually stored in a digital memory of large capacity such as magnetic disk memory, those data are read out by each color original picture, reproducing images are editted while being displayed on an interactive CRT monitor, for example, based on the layout designation, and an output unit is controlled according to the edited data so as to obtain the reproduced image by each color plate.
(2) Prior Art
In the known image processing system such as layout scanner system, the image data produced by the system, i.g., a plurality of line drawings and figures such as color picture images having variable density or characters read by the system separately are once written in a memory for provisional storage, and then the editing operation is performed by rearranging the image data respectively at their suitable positions on the memory for editing plate based on the layout designation. In this process, a method for rapidly performing the editing operation while confirming it visually is adopted i.e., in addition to the digital memory of large capacity such as magnetic disk to be a memory for said step of provisionally storing each of read individual image data and that for the step of editing plate, a refresh memory for storing specially condensed image data which are read for interaction with the operator is provided so as to display an image corresponding to the image data on the color monitor.
In this connection, when the color original picture for use in the color layout scanner is written in the memory, even in case of a relatively small-sized one, it is necessary to have the memory of extremely large capacity because of abundance in resolving power and tone thereof, and therefore considering the cost per bit, transfer speed, disposing space, etc., a magnetic disk is conventionally used as said memories.
However, the data transfer speed of the magnetic disk device is not so sufficient that, even though the factors for the optimum arrangement can be decided by the interaction with the color monitor, when the data transfer from the memory for provisional storage to the memory for editing plate is started according to the command of rearrangement, it is necessary for the next step to wait for a while, i.e., the next step is unavoidably delayed and the editing speed of the page as a whole is not improved so much. Even when the editing operation on the color monitor is off-line with the editing operation of magnetic disk data, there still remains a problem that the latter operation takes much time.
In this sense, it may be an idea that since the color picture image having variable density is separated into signals of four color plates C, M, Y, K (or R, G, B, occasionally) in the ordinary graphic arts, the image signal corresponding to each color plate signal is individually stored in 4 (or 3) magnetic disk devices, and another 4 (or 3) magnetic disk devices for editing plate are prepared for the editing operation so as to be operated simultaneously for each color plate, thereby achieving the speed-up in the editing operation. In this case, however, 8 (or 6) magnetic disk devices are required in total, and it is not only uneconomical but the necessary labor for replacing magnetic disk packs after completing the editing operation becomes quadruple.
Thus, the known layout scanner system is not always sufficiently practical and is therefore principally used for creative graphic arts of high value added such as industrial design.